Genetic counseling and carrier screening in candidates for gamete donation at a Portuguese center.

OBJECTIVE

Genetic counseling and carrier screening are part of the gamete donation process by healthy individuals. We aim to review the findings of genetic counseling and carrier screening of a cohort of candidates at our public gametes bank.

METHODS

Thirty-four male and 64 female candidates had genetic counseling with a medical geneticist before donation. Of these, one female candidate voluntarily dropped-out. Thirty-four males and 63 females performed karyotype and screening for the more common pathogenic variants for CFTR-related cystic fibrosis and spinal muscular atrophy (SMN1) in the Portuguese population. In addition, all females also performed Fragile X expansion screening (FMR1). Thirty candidates with known or assumed African ancestry performed hemoglobinopathies screening.

RESULTS

Six candidates were definitely or temporarily withheld from the donation process given their family or personal history that required further investigation. Of 97 candidates tested, 16.5% presented anomalous laboratory results (16/97): ten candidates were carriers for an autosomal recessive disorder - cystic fibrosis (5/97), sickle cell anemia (3/30), and spinal muscular atrophy (2/97). One female was an FMR1 pre-mutation carrier (1/63). One female candidate presented with triple X mosaicism: 47,XXX[2]/46,XX[50]. Two candidates presented with chromosomal instability of unknown origin. In one candidate, a mosaic for the Philadelphia chromosome was detected, revealing the diagnosis of chronic myeloid leukemia.

CONCLUSIONS

From a cohort of 97 candidates, 21.7% had a family/personal history or an anomalous laboratory result that required additional genetic counseling, stressing the importance of performing pre-donation genetic counseling in this population.